Fuel injection pump



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CRA NK CAM ANGLE IN DEG REES INVENTORZ MAX H. VOIGT av April 29, wa M.H. vols? 3,M@,@4

FUEL INJECTION PUM? Filed Dec. 9, 1966 7 Sheet 3 of 2 INVENTOR'.

MAX H. VOIGT United States Patent Office Patented Apr. 29, 19693,440,964 FUEL INJECTION PUMP Max H. Voigt, Chicopee Falls, Mass.,assignor to AMBAC Industries, Incorporated, Springfield, Mass., acorporation of New York Filed Dec. 9, 1966, Ser. No. 600,474 Int. Cl.F04b 13/02, 49/00 US. Cl. 1032 Claims ABSTRACT OF THE DISCLOSURE Thepresent invention relates to fuel injection pumps of the single plunger,distributor type such as that shown in US. Patent 2,518,473, issued Aug.15, 1950, and assigned with the present application to a commonassignee. In this type of pump, a reciprocating and rotating plungerpumps fuel from a fuel distribution chamber sequentially to thecylinders of the fuel injection engine on which it is mounted, eachstroke of the plunger supplying an injection of fuel to an enginecylinder by means of a fuel injection nozzle. Fuel is supplied to thedistribution chamber by a fuel supply pump, the fuel entering thechamber through supply passages which are fully open to the chamber onlyat the bottom of the plunger stroke. The amount of fuel pumped to theengine is controlled by means of an axial bore in the plunger which, inconjunction with radial spill ports, connects the fuel distributionchamber with a sump in which fuel is maintained at the fuel supplypressure. An adjustably positioned control sleeve on the plunger in thesump covers the spill ports during the pumping portion of the plungerstroke. When the spill ports clear the sleeve, the fuel distributionchamber pressure is reduced to the supply pressure, causing a checkvalve to close and thus terminating the fuel injection.

Difliculties have been experienced with this type of pump at high speedin maintaining the full discharge capacity of the pump. This is due tothe failure of the fuel distribution chamber to fill with the necessaryvolume of fuel, even at increased fuel supply pressures. A furtherproblem with this type of pump has resulted from the vacuum conditioncaused during the return stroke of the plunger after the spill portshave been reclosed and before the fuel supply passages have been opened,the chamber pressure during this period dropping below the vaporpressure of the fuel. The repeated collapse of the vacuum andtransformation of the fuel from the vapor to the liquid phase causescavitation erosion of the fuel supply ports and fuel distributionchamber. A further difficulty with the conventional pump is thepossibility of reverse engine operation, for example following a falsestart, which can result in costly damage to the engine.

To correct the above difiiculties, the present invention comprises theimprovement of supplementary filling means for filling the fueldistribution chamber during the entire downstroke of the plunger. Thesupplemental filling means includes supplementary ports in the plungerand complementing supplementary conduits in the hydraulic head plungerbore communicating with the fuel supply.

The supplementary plunger ports and hydraulic head conduits are soarranged as to provide communication between the fuel distributionchamber and the fuel supply sump during the entire downstroke of theplunger. In addition, should the engine attempt to operate in reverse,the supplemental ports and conduits communicate during the compressionstroke of the plunger thereby preventing the compression of fuel in thefuel distribution chamber and effectively preventing reverse engineoperation.

In view of the above, it is asfirst object of the present invention toimprove the fuel filling efiiciency of the fuel distribution chamber ofa single plunger, distributor type fuel injection pump by means ofcomplementing supplementary ports in the plunger and conduits in thehydraulic head to provide communication of the chamber with the fuelsupply during the downstroke of the plunger in addition to the fuelinflow through the regular fuel inlet ports.

A further object of the invention is to provide an improved tuel fillingmeans as described operable during the entire downward stroke of theplunger to prevent fuel vaporization and the resultant cavitationdamage.

Another object of the invention is to provide fuel filling means asdescribed which provides an efiicient fuel distribution chamber fillingeven at high engine speeds with a normal fuel supply pressure.

A still further object of the invention is to provide supplementary fuelfilling means as described which will permit normal operation of theengine in its prescribed rotational direction but which will prevent theengine from running in the reverse direction.

Additional objects and advantages of the invention will be more readilyapparent from the following detailed description of an embodimentthereof when taken together with'the accompanying drawings, in which:

FIG. 1 is a partial sectional view taken through a fuel fuel injectionpump embodying the present invention and showing the pump plunger in thebottom dead center position;

FIG. 2 is a sectional view taken along line 22 of FIG. 1;

FIG. 3 is a partial view taken as in FIG. 1 showing the portion of thepump hydraulic head surrounding the upper end of the plunger at thebottom dead center plunger position;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3 showing thesupplementary plunger ports and their relation to the supplementalconduits in the hydraulic head at the plunger bottom read centerposition;

FIG. 5 is a view similar to FIG. 3 showing the plunger at the top deadcenter position;

FIG. 6 is a sectional vew taken along line 66 of FIG. 5 and showing asin FIG. 4 the relationship of the supplemental ports and conduits;

FIG. 7 is a view similar to FIGS. 3 and 5 showing the plunger part waythrough the plunger downward stroke just before the opening of the mainfuel supply passages;

FIG. 8 is a sectional view taken along line 88 of FIG. 7 and showing asin FIGS. 4 and 6 the relationship of the supplemental ports andconduits; and

FIG. 9 is a graph relating the engine rotation to the plunger movementthrough its cycle of operation and indicating the sequence of openingand closing of the various fuel filling means.

Referring to the drawings, and particularly FIGS. 1 and 2 therefore, afuel injection pump 10 of the general type illustrated in theabove-mentioned Patent 2,518,473, is shown in part including a hydraulicpump head 12 mounted on the main pump housing 14. The hydraulic pumphead 12 includes a central vertical bore 16 within which a plunger 18 isslidably disposed, the plunger in conjunction with the threaded boreplug 20 defining a fuel distribution chamber 22 in the upper end of thebore. The plunger passes through a sump or spill chamber 24 in the lowerpart of the hydraulic head and is rotatably and reciprocally driven fordelivering fuel to cylinders of an internal combustion engine (notshown) in a manner to be presently described.

The pump is driven by the engine by means of the camshaft 26 which issuitably journaled in the main housing 14. A cam 28 on the camshafthaving a plurality of cam lobes 30 coacts with roller 32 of tappet 34,and in conjunction with helical return springs 36 and 38 effects areciprocating vertical stroke of the plunger. Rotation of the plunger iseffected by means of a vertical quill shaft (not shown) geared to thecamshaft and having a gear at the upper end thereof meshing with thesliding gear 40 on the plunger. The rotation of the camshaft 26 thuscauses both a reciprocation and rotation of the plunger resulting in thecyclical plunger movement graphically illustrated in FIG. 9.

The hydraulic pump head 12 includes fuel inlet ports 42 and 44 onopposite sides thereof to which fuel under pressure is supplied by asuitable fuel supply pump (not shown). The inlet ports 42 and 44communicate respectively with the fuel supply passages 46 and 48 whichin turn open into the fuel distribution chamber 22. The pressurized fuelpasses through the passages 46 and 48 into the fuel distribution chamberwhen the plunger exposes the passages to the chamber and is pumpedsequentially to the cylinders of the engine by the upward strokes of theplunger, the fuel in the chamber being forced through fuel deliverycheck valve 50 as shown in FIG. 2. Fuel flowing through the check valvepasses around the valve plunger 52 and through passages 54 and 56 in theplug 58 to an annulus 60 in the plug. The fuel flows from the annulus 60through passage 62 in the pump head into the annulus 64 of the plungerand then into the plunger groove 66, which sequentially communicateswith spaced distributor passages 68 in the pump head during rotation ofthe plunger. Each distributor passage 68 communicates with an outletpassage 70 from which fuel is discharged through outlet ports 72 to thecylinders of the engine, the cylinders being connected thereto by meansof suitable tubing. The number of ports 72 corresponds, of course, withthe number of cylinders in the engine, the present pump having six portsand thus being adapted to provide fuel for a six cylinder engine. Therotation of the plunger is timed to sequentially position the plungergroove 66 in alignment with the distributor passages for delivery offuel to tlhe cylinders in the proper phase relation to the engine cyc e.

The amount of fuel delivered by the pump is regulated by the position ofthe control sleeve 74 slidably located on the plunger in the sump 24 ina manner to be presently described. The control sleeve 74 is verticallypositioned on the plunger within the sump 24 by means of a conventionalstub shaft and eccentric pin connected with the control rod linkage fromthe governor, none of which is shown in the present drawings in view ofits completely conventional character. The plunger includes an axialbore 76 which extends from the upper end of the plunger to the radialspill ports 78 communicating with the sump 24. When the spill ports 78are covered by the control sleeve 74, fuel cannot pass from the fueldistribution chamber through bore 76 to the sump. However, when thespill ports clear the sleeve toward the end of the plunger pumpmgstroke, the pressure in the distribution chamber is reduced to the sumppressure, permitting the check valve 52 to close and stopping furtherfuel delivery. By adjustment of the vertical sleeve position, theduration of the pumping action and hence the amount of fuel deliveredmay be accurately controlled.

A pair of downwardly inclined fuel conduits 80 and 82 extend from thefuel inlet ports 42 and 44, connecting the inlet ports with an annularhead sump 84 which is connected with the sump 24 by a port (not shown)to provide the fuel supply pressure in the sump 24.

The fuel injection pump structure and operation as described so far areconventional and are in most respects similar to that of theabove-mentioned US. Patent 2,518,- 473. It can be understood from theabove description that during the return or suction stroke of theplunger, a period exists during which both the spill ports 78 and thefuel supply passages 46 and 48 are respectively closed by the controlsleeve and the plunger. This period is prolonged when the control sleeveis set at an elevated position in the sump such as at maximum fueldelivery. In order to prevent a vacuum condition in the fueldistribution chamber during this period and consequent caviation erosionof the chamber and fuel passages, and further to insure the filling ofthe fuel distribution chamber over a full range of engine speeds with anormal fuel supply pressure, a supplementary fuel distribution chamberfilling means is provided as described below. As will be noted from thedescription of the filling means, this arrangement also serves toprevent reverse operation of the engine and the serious damage to theengine which can result therefrom.

The supplemental filling means comprises a plurality of radialsupplemental ports in the plunger communicating with the plunger bore 76and located below the plunger annulus 64 but above the sump 24. Thesupplemental plunger ports in the present embodiment comprise threeupper ports 86 radiating at 120 angles from the plunger bore and threelower ports 88 in closely spaced relation therebelow similarly radiatingfrom the plunger bore at 120 angles in staggered relation to the ports86, there thus being a port radiating from the plunger bore at each 60of the plunger circumference as illustrated in FIGS. 4, 6 and 8.

Complementing the plunger ports 86 and 88 are a plurality ofsupplemental conduits 90 connecting the hydraulic head bore 16 with theannular head sump 84. The supplemental conduits 90 are six in number andare spaced at exactly 60 intervals so as to complement the six plungerports 86 and 88 during operation of the pump in a manner to be describedbelow. The point of connection with the conduits 90 with the plungerbore 16 is such that the upper row of plunger ports 86 are horizontallyaligned for communication with the conduits at bottom dead center asshown in FIGS. 1 and 3 while the lower plunger ports 88 are horizontallyaligned for communication with the conduits at top dead center as shownin FIG. 5. The importance of the proper circumferential location of theconduits 90 with respect to the plunger ports 86 and 88 will be apparentfrom the following description of the operation of the supplementalfilling means. 5

Referring to the graph of FIG. 9, with-'the camshaft 26 rotating atone-half engine speed, a full cycle of the injection pump will occurevery of engine crankshaft rotation using the six lobe cam 28. On theupstroke or pumping stroke of the plunger, the plunger covers the fuelsupply passages 46 and 48 at point A on the graph, at which pointcompression and pumping of the fuel in the fuel distribution chamber byway of the check valve 52 and connected passages begins as describedabove. Pumping of the fuel continues until the spill ports 78 of theplunger rise above the control sleeve 74 at a given setting of thecontrol sleeve which may for example be at point B on the graph. Sincefuel from the fuel distribution chamber may now escape through the bore76 of the plunger and through spill ports 78 into the sump 24,compression of the fuel in the fuel distribution chamber stops at pointB and the check valve 52 closes.

As the plunger reaches point C at top dead center, the spill ports 78are still in communication with the sump and remain in communicationtherewith until point D on the graph is reached, at which point thespill ports return w thin the control sleeve which cuts oil? communi atiwlth the sumP- Since the P ger does not uncover the fuel p y P ges 46and 48 until point B on the graph has been reached, in the absence ofthe supplemental filling means of the present invention, it can beunderstood that from point D to point E on the graph there would be aperiod of rapidly decreasing pressure within the fuel distributionchamber during which period fuel vaporization and the resultantcavitation on breaking of the vacuum condition occurs. Prior to thepresent invention, it can be understood that the filling of the fueldistribution chamber took place only from points C to D following by thedescribed interruption, and then from point B through point F at bottomdead center back to point A while the fuel supply passages are exposed.

With the present supplemental filling means, as shown in FIGS. 5 and 6,at top dead center, represented by point C on the graph, the spill ports78 are in communication with the sump 24 and, at the same time, thesupplemental ports 88 are just beginning to rotate into communicationwith the supplemental conduits 90, adding a further source of fuel inputto the fuel distribution chamber, the fuel entering from the annularhead sump 84 through the conduits 90, ports 88, and the bore 76 of theplunger into the fuel distribution chamber.

Midway through the downstroke or suction stroke of the plunger, as shownin FIGS. 7 and 8, the supplemental ports 88 and 86 have rotated intoradial alignment with the supplemental conduits 90 and the downwardmovement of the plunger has brought both rows of supplemental ports intocommunication with the conduits. At this point, the fuel supply passages46 and 48 have still not been uncovered by the downward plunger movementalthough, and as can be seen from FIG. 7, the spill ports 78 are withinthe control sleeve 74 so that the supplemental ports and conduits are atthis point providing the only source of fuel input to the fueldistribution chamber.

At the bottom dead center plunger position shown in FIGS. 3 and 4, thesupplemental ports 86 are horizontally aligned with the conduits 90 asshown in FIG. 3 but are just being rotated out of phase with theconduits as shown in FIG. 4 to prevent further fluid communicationtherewith. It can thus be seen that the supplemental ports and conduitsprovide a supplemental fuel input to the fuel distribution chamberthrough out the entire downstroke or suction stroke of the plunger fromthe point C to point F on the graph of FIG. 9.

By supplementing the interrupted fuel input heretofore provided only bythe spill ports from point C to point D and by the fuel supply passages46 and 48 from point E through point A, the present supplemental fillingmeans can be understood to provide a greatly improved filling efficiencyof the pump. The supplemental filling effect is, of course, in additionto the conventional filling arrangement so that filling of the fueldistribution chamber continues from point B when the spill ports 78 openthrough the remainder of the upstroke, the entire 'downstroke, and thebeginning of the subsequent upstroke to point A at which point the fuelsupply passages 46 and 48 are closed. Fuel is thus continuously suppliedto the fuel distribution chamber during the plunger cycle except frompoint A to point B during compression and injection of the fuel.

The supplemental conduits 90 and complementing supplemental ports 86 and88 serve a further important function in preventing the reverseoperation of the engine. Should the engine start to rotate in a reversedirection such as following a false start, the pump being coupled to theengine will also rotate in a reverse direction and the pumping stroke ofthe plunger as represented on the graph of FIG. 9 will now extend to theleft from point P to point C, which is the portion of the cycle duringwhich the supplemental ports 86 and 88 remain in continuouscommunication with the conduits 90. Upward movement of the plungerduring a reverse rotation of the pump cannot compress the fuel in thefuel distribution chamber since communication of the chamber with thehead sump 84 is continuously provided by the supplemental ports andconduits throughout the reverse pumping stroke of the plunger. The checkvalve 52 is thus never open during reverse operation of the pump and nofuel is injected into the engine, effectively preventing reverse engineoperation.

The number of supplemental conduits and supplemental ports isconveniently chosen to coincide with the number of outlet ports 72 inthe pump. In the present instance, with a six cylidner engine, there areaccordingly six conduits and six complementing plunger ports. A similarsystem could, of course, be provided for a four or an eight cylinderengine with the same principles being utilized to provide a supplementalfuel distribution chamber filling means.

From the foregoing it can be understood that the invention presentedcarries out all of the foregoing objects in providing a supplementalfilling means for a distributor type injection pump which insures anefficient pump filling even under high speed engine operation withnormal fuel supply pressures (1560 p.s.i.). Cavitation erosion issignifipantly reduced by the present invention and reverse engineoperation is effectively prevented.

Manifestly, changes in details of construction can be effected by thoseskilled in the art without departing from the spirit and the scope ofthe invention as defined in and limited solely by the appended claims.

I claim:

1. In a fuel injection pump including a hydraulic head having a boretherein, a plunger rotatably and slidably disposed within the bore, thebore end above the plunger comprising a fuel distribution chamber, afirst sump spaced from the chamber surrounding the plunger, an annularsecond sump radially spaced from and interconnected with said firstsump, fuel supply means for delivering fuel to the fuel distributionchamber and to said sumps, said fuel supply means including at least onefuel supply passage in said hydraulic head bore opening directly intosaid fuel distribution chamber during a por tion of the plunger cycle,fuel delivery means operable to deliver fuel sequentially from the fueldistribution chamber to cylinders of an engine in a predetermined orderduring compression strokes of the plunger, passage means in the plungerconnecting the fuel distribution chamber and said first sump, and anadjustable control sleeve slidably mounted on the plunger in said firstsump which may be selectively positioned to control the opening of saidpassage means in the plunger during the plunger compression stroke tocontrol the amount of fuel discharged from the fuel distribution chamberto the engine, the improvement comprising supplemental filling means forproviding a supplemental fuel filling of said fuel distribution chamberduring the entire suction stroke of said plunger, said supplementalfilling means comprising at least one supplemental port in said plungerextending radially from said plunger passage means and at least onecomplementing supplemental conduit in said hydraulic head adapted toprovide fluid communication between said annular second sump and saidsupplemental plunger port during the entire suction stroke of saidplunger, said supplemental port being phased out of communication withsaid supplemental conduit during the compression stroke of the plungerby the plunger rotation.

2. The improvement as claimed in claim 1 wherein said supplemental portis in communication with said supplemental conduit throughout thesuction stroke of said plunger.

3. The improvement as claimed in claim 1 wherein said supplemental portsand conduits are disposed between said fuel distribution chamber andsaid first sump.

4. The improvement as claimed in claim 1 wherein said supplementaryfilling means comprises an equal number of supplementary ports andsupplementary conduits.

7 8 5. The improvement as claimed in claim 4 wherein 3,186,396 6/1965Nystrom et al. said supplementary filling means comprises a number3,320,892 5/1967 Wolff 103-2 of supplementary ports and supplementaryconduits cor- 3,311,062 3/1967 Knapp et a1. 103-2 responding to thenumber of outlet ports of the pump. 3,348,488 10/1967 Wolff.

References Cited 5 ROBERT M. WALKER, Primary Examiner. UNITED STATESPATENTS W. J KRAUSS,Assistant Examiner. 2,965,087 12/1960 Bischofi etal. 123-140 3,011,490 12/1961 Bischoif 123 139 3,138,103 6/1964 Dreisinetal. 103-41

